The present invention relates to a switching type AC adapter, and more particularly to such a switching type AC adapter in which a current mode PWM (pulse-width-modulated) controller, a monostable multivibrator, and a MOSFET are installed, and operated to eliminate presence of horizontal synchronizing interference on the screen.
A regular switching type AC adapter for an electric apparatus is comprised of a switching element, which is alternatively switched on and off to let a stable voltage be provided to the electric apparatus for working. When this structure of switching type AC adapter is used in a monitor, voltage waveform and current waveform are changed quickly upon switching of the switching element, causing the displayed picture to be interfered with an interference. More particularly, when this structure of switching type AC adapter is used in a television set, image signal which was converted from radio signal by a tuner tends to be interfered with harmonic waves, causing the picture to be distorted.